Issue #9632 has been updated by Akira Tanaka.


 2014-05-11 8:50 GMT+09:00 Eric Wong <normalperson / yhbt.net>:
 > Eric Wong <normalperson / yhbt.net> wrote:
 >> Any comment?  My main concern is it's a large import of new code;
 >> but it is also highly reusable.  I'll commit in 2-4 weeks if no response.
 >> The 0002 patch can wait longer.
 >
 > Committed as r45913.  Hopefully nothing breaks, I tested extensively
 > on my "production" server.  Sorry for the delay, was busy.
 
 I found that doxygen produces many warnings in ccan/ directory.
 http://www.rubyist.net/~akr/chkbuild/debian/ruby-trunk/log/20140510T235500Z.diff.html.gz
 
 It seems the comments in ccan/ directory is not doxygen-compatible.
 
 Anyone use doxygen?
 If no one use it, we can drop doxygen support.
 (It makes the CI faster.)
 -- 
 Tanaka Akira

----------------------------------------
Feature #9632: [PATCH 0/2] speedup IO#close with linked-list from ccan
https://bugs.ruby-lang.org/issues/9632#change-46708

* Author: Eric Wong
* Status: Open
* Priority: Normal
* Assignee: Koichi Sasada
* Category: core
* Target version: current: 2.2.0
----------------------------------------
This imports the ccan linked-list (BSD-MIT licensed version of the Linux kernel
linked list).  I cut out some of the unused str* code (only for debugging),
but it's still a big import of new code.  Modifications to existing code is
minimal, and it makes the living_threads iteration functions simpler.

The improvement is great, and there may be future places where we could
use a doubly linked list.

= vm->living_threads:

* before: st hash table had extra malloc overhead, and slow iteration due
to bad cache locality

* after: guaranteed O(1) insert/remove performance (branchless!)
iteration is still O(n), but performance is improved in IO#close
due to less pointer chasing


= IO#close: further improvement with second linked list

* before: IO#close is linear based on number of living threads
* after: IO#close is linear based on number of waiting threads

No extra malloc is needed (only 2 new pointers in existing structs)
for a secondary linked-list for waiting FDs.


I chose the ccan linked list over BSD <sys/queue.h> for two reasons:
1) insertion and removal are both branchless
2) locality is improved if a struct may be a member of multiple lists

git://80x24.org/ruby.git threads-list


---Files--------------------------------
0002-speedup-IO-close-with-many-living-threads.patch (2.86 KB)
0001-doubly-linked-list-from-ccan-to-manage-vm-living_thr.patch (68.1 KB)


-- 
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